If the belt is "pretty" loose right now that is bad...thats BAD! and you want to do the tensioner while your doing the belt. It just makes good sense. Both pulleys AND your crankshaft keyway should be spot on!! A tooth off one way or the other the motor will usually idle. But motor has no power and will run like crap/backfire ect. OH a correction! The above says to install the belt in a clockwise fashion. THATS a TYPO Start at the crank and go counter clockwise so all the teeth and cogs line up tight before you release the tension on the idelr pully. I used a wooden hammer handle against the wheel on the new tensioner pulley and pushed to the left with all my might and my girlfriend tightend the bolt that holds it out of the way. THEN I started threading the new belt on snuggly held the slck tight and loosend that bolt to let the tensioner release and put pressure on the belt. With the pulley still off the crank put the bolt back in and turn the crank clockwise a few times and make sure all your marks line up still. Without removing the radiator you wont be able to get that big cheap harbor freight impact gun in there. Thats for sure! I didnt use my impact gun. I used a big breaker bar to bust it loose and a long tourque wrench AND lock tite to reinstall. The radiator is so easy to take out I just did it so I could clean the inside AND the fins....shroud....timing belt cover and inspected both hoses. I used new clamps is all. All my stuff looked OK. Please dont dump coolant on the ground. What drips/spills towel it up! It is sweet and atracts animals...and it will kill them in a slow painful cruel way.

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Red 1994 Mazda B2300 Base Model With A/C--2.3L--140cid-100hp--4Cyl--D.I.S. Engine Code [A]--Bosch (4505) Fusion Iradium Spark Plugs-- "Cheap" 8mm Silicone Plug Wires--Gatorback Belt--Blocked Off/Disabled EGR Valve--Coil Mod--Throttle Cable Mod--Magnaflow Muffler/No CAT--5 Speed M5R1-RWD--3.45 Non Limited Slip Rear End---Lowered 5" Rear 3 1/2" Front---269,000 Miles as of 11/1/2013---If its a Ford you will need to keep a lot of tools and a good fire extinguisher handy.